US8100881B2 - Flexible medical device for clot removal from small vessels - Google Patents

Abstract

A medical device and method of applying said medical device to deliver drugs and to remove thrombus or soft tissue clots from vascular or other lumens in a patient is presented. The medical device generally comprises an elongated tubular delivery member having a proximal portion and a distal portion that differ in rigidity and a leak-free connector that is in contact with the proximal portion of the delivery member and is compatible for use with fibrinolytic agents and application of a vacuum. The delivery member includes a metal core made out of multiple shaped-wire strands and a polymer overlay disposed about the core. The wire strands, which have both an A-side and a B-side, are helically wound to form a polygonal shaped lumen whose inner diameter is defined by the A-side of the strands.

Description

FIELD

This invention relates generally to medical devices used in the vasculature of a patient and more particularly to devices used to deliver drugs and to remove thrombus or soft tissue clots from vascular or other lumens in a patient.

BACKGROUND

Since small vessel emboli (e.g., intracranial clots) are usually difficult to remove mechanically due to the limited size of the vessel, catheter-directed fibrinolysis is frequently considered to be the best available treatment. The goal associated with catheter-directed fibrinolysis is to deliver a fibrinolytic agent directly to a thrombus in order to activate the plasminogen bound to the fibrin clot. In order to achieve this goal, an infusion catheter or wire is typically embedded within the thrombus and a fibrinolytic agent, such as a tissue-type plasminogen activator (t-PA), is continuously infused through the catheter at a rate of 1-2 mg per hour until successful dissolution of the thrombus is achieved between 12-18 hours later.

One problem routinely encountered during such catheter-directed fibrinolysis is pericatheter thrombosis. Pericatheter thrombosis results from poor blood flow along the length of the catheter. In order to decrease the incidence of this problem, a low dosage of intraveneous heparin (500-1000 units/hr) is frequently introduced into the vessel through the catheter's sheath. Anticoagulation with heparin is also known to be helpful to prevent rebound thrombosis after the fibrinolytic infusion is completed. Additional methods used to reduce the occurrence of pericatheter thrombosis is to keep the intravascular length of catheter to a minimum, to use a catheter with the smallest possible diameter, and to reduce the overall length of time associated with the infusion.

An additional complication that can be encountered during catheter-directed fibrinolysis is related to the occurrence of bleeding at the arterial puncture site. This type of complication is usually considered minor, but can be life threatening if it occurs at a remote site (i.e., intracranial, etc.). The risk associated with the occurrence of this complication is known to increase with the length of time associated with the infusion.

Accordingly, there exists a need to reduce the risks associated with catheter-directed fibrinolysis in small vessels. In particular, there exists a need to deliver the necessary dosage of fibrinolytic agent to achieve complete dissolution of the emboli over the shortest duration of time, while maintaining the minimum necessary diameter and length for the catheter used for the infusion.

SUMMARY

The present invention provides a medical device for clot removal from small vessels by fibrinolytic infusion or vacuum retrieval. One embodiment of a medical device, constructed in accordance with the teachings of the present invention, generally comprises an elongated tubular delivery member having a proximal portion and a distal portion and a leak-free connector that is in contact with the proximal portion of the delivery member and is compatible for use with fibrinolytic agents and application of a vacuum.

The delivery member is comprised of a metal core made out of multiple shaped-wire strands and a polymer overlay disposed about the metal core. The wire strands, which have both an A-side and a B-side, are helically wound to form a lumen whose inner diameter is defined by the A-side of the strands.

Geometrically, the helically wound wire strands form a first polygon defined by the B-side of the strands and a second polygon defined by the A-side of the strands. The second polygon defines the shape of the delivery member's lumen. The first polygon is further defined to inscribe a first circle having a radius, R₁, and the second polygon circumscribes a second circle having radius, R₂. The difference in magnitude between R₁and R₂is about equal to the thickness of the wire strands. The ratio of the area (A1) of the first polygon to the area (A2) of the second polygon is about equal to the quotient of [(R₁)²·cos²(π/N)]/(R₂)², where N is the number of wire strands.

Another aspect of the delivery member of the present invention divides said member into proximal and distal portions with each portion being different in their predetermined degree of rigidity. The difference in rigidity between the proximal and distal portions can result from a variation in one of the wall thickness of the metal core, the hardness of the overlay, and a combination thereof. The variation in wall thickness of the core may result from a grinding operation being performed on the outer diameter of the corers distal portion. The variation in wall thickness of the hollow core may also result from using at least one different core for the proximal portion and the distal portion that have substantially similar inner diameters, but different outer diameters.

Another objective of the present invention is to provide a method for clot removal from small vessels by fibrinolytic infusion or vacuum retrieval. This method comprises the steps of introducing a sheath having a lumen into a blood vessel; inserting a guide wire through the lumen of the sheath; deploying the elongated tubular delivery member of the medical device of the present invention; positioning the distal end of the delivery member of the medical device proximate to a clot; removing the guide wire; injecting a fibrinolytic agent into the blood vessel through the delivery member until the clot is dissolved; and removing the delivery member of the medical device from the blood vessel. The method may further comprise the steps of applying a vacuum through the delivery member to a clot that is only partially dissolved and removing the partially dissolved clot via the vacuum.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a perspective view of a medical device used for removal of a clot from a patient's vasculature having a delivery member and a leak-free connector according to the teachings of the present invention;

FIG. 2 is an axial cross-sectional view of the delivery member used in the medical device ofFIG. 1 according to one aspect of the present invention;

FIG. 3 is a geometric representation of the cross-sectional area of the delivery member used in the medical device ofFIG. 1 according to one aspect of the present invention;

FIG. 4 is an axial cross-sectional view of the delivery member of the medical device ofFIG. 1 according to another aspect of the present invention;

FIG. 5A is a cross-sectional view of a wire strand having a half-round shape according to one aspect of the present invention;

FIG. 5B is a cross-sectional view of a wire strand having less than half-round shape according to another aspect of the present invention;

FIG. 5C is a cross-sectional view of a wire strand having pie shape according to another aspect of the present invention;

FIG. 5D is a cross-sectional view of a wire strand having a triangular shape according to another aspect of the present invention;

FIG. 5E is a cross-sectional view of a wire strand having a rectangular shape according to another aspect of the present invention;

FIG. 5F is a cross-sectional view of a wire strand having a square shape according to another aspect of the present invention;

FIG. 5G is a cross-sectional view of a wire strand having flat shape according to another aspect of the present invention;

FIG. 5H is a cross-sectional view of a wire strand having half moon shape according to another aspect of the present invention;

FIG. 6 is a longitudinal cross-sectional view of the delivery member of the medical device ofFIG. 1 according to yet another aspect of the present invention; and

FIG. 7 is a schematical representation of a method for using the medical device ofFIG. 1 for the removal of emboli according to the teachings of the present invention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. It should be understood that throughout the description and drawings, corresponding reference numerals indicate like or corresponding parts and features.

Referring toFIG. 1 amedical device10 for intracranial clot removal according to the present invention is shown having adistal end30, an elongatedtubular delivery member15 extending from thedistal end30 to aproximal end35. Thedelivery member15 has both aproximal portion20 and adistal portion25 with theproximal portion20 being in contact with a leak-free connector40 that is compatible for use with fibrinolytic infusion, vacuum retrieval methodology, or both. Theproximal portion20 and thedistal portion25 of thedelivery member15 may be different in their predetermined degree of rigidity.

Referring now toFIG. 2, thedelivery member15 is comprised of ametal core52 of helically woundmultiple wire strands50A. Eachwire strand50A has an A-side47 and a B-side48 with the A-side47 of the combinedstrands50A forming a centrallongitudinally extending lumen45. Each of the metal strands has a width and thickness defined as W₁and T, respectively. Apolymer overlay55 is disposed about themetal core52 or about the B-side48 of thewire strands50A. The helically woundwire strands50A geometrically form a first polygon defined by the B-side48 of thestrands50A and a second polygon defined by theA-side47 of thestrands50A.

InFIG. 3, the geometry associated with themetal core52 is further described. The B-side48 and theA-side47 of the helically woundwire strands50A form afirst polygon70 and asecond polygon75, respectively, with the second polygon defining the shape of thelumen45 of themetal core52. The polygonal shape of thelumen45 is preferable in order to maintain a wide open working channel or lumen through which a fibrinolytic agent may be delivered to a clot or thrombus. This wide open channel or lumen allows for the fibrinolytic agent to be effectively delivered in the shortest amount of time.

Thefirst polygon70 can be shown to inscribe afirst circle80, while thesecond polygon75 is shown to circumscribe asecond circle85, respectively. Thefirst circle80 may further be defined as having a radius, R₁. The inscribedfirst polygon70 may be defined by N-sides (S₁) with the length of each side being further described by the relationship shown in Equation1. Thesecond circle85 may further be defined as having a radius, R₂. The circumscribedsecond polygon75 may be defined by N-sides (S₂) with the length of each side being further described by the relationship provided inEquation 2. InEquations 1 and 2, N represents the number ofwire strands50A used to form thewire core52. The difference between R₁and R₂is due to the thickness (T) associated with thewire strands50A.
S₁≈2·(R₁)·sin(π/N)  Eq. 1
S₂≈2·(R₂)·tan(π/N)  Eq. 2

The cross-sectional area (A₁) of thefirst polygon70 can be described by the relationship depicted in Equation 3. Similarly, the cross-sectional area (A₂) of thesecond polygon75 can be described by the relationship shown in Equation 4. Upon combiningEquations 1 and 2 with Equations 3 and 4, respectively, followed by trigonometric reduction using the known fundamental identity for tan(x)=sin(x)/cos(x), the ratio of the area (A₁) of thefirst polygon70 to the area (A₂) of thesecond polygon75 is derived to be about equivalent to the relationship provided in Equation 5. The polygonal shape of themetal core52 provides for a cross-sectional area (A₂) of thelumen45 formed therein to be greater than the circular cross-sectional area of a lumen formed by conventional helical wire winding that has a radius equivalent to R₁.
A₁≈[N·(S₁)²]/[4·tan(π/N)]  Eq. 3
A₂≈[N·(S₂)²]/[4·tan(π/N)]  Eq. 4
A₁/A₂≈[(R₁)²·cos²(π/N)]/(R₂)²  Eq. 5

Referring now toFIG. 4, thedelivery member15 may further comprise a second layer of helically woundmultiple wire strands50B where theA-side51 of thewire strands50B of this second layer are disposed about the B-side48 of the first layer of helicallywound wire strands50A. Although this second layer ofwire strands50B is similar to the first layer ofwire strands50A in the number of strands, it differs in that the width (W₂) of each strand in the second layer is larger than the width (W₁) of each strand in the first layer. Although the use of a second layer ofwire strands50B can enhance the impermeability of thedelivery member15, it also may reduce the flexibility of thedelivery member15. When a second layer is used as part of themetal core52 the polymer overlay is disposed about the B-side53 of thewire strands50B.

Thedelivery member15 of themedical device10 may be a catheter that is normally open ended at both the proximal35 and thedistal end30. Such a catheter can be used for the intracranial removal of a clot after subjecting said clot to fibrinolytic infusion and/or assisting the removal of the clot through the application of a vacuum. One skilled-in-the-art will recognize that themedical device10 of the present invention may be useful in a variety of other applications, including but not limited to percutaneous transluminal coronary angioplasty, drug delivery, and as a guiding catheter.

Thewire strands50A that are helically wound into themetal core52 may be comprised of any linear elastic material, including but not limited to stainless steel platinum alloys, titanium, tantalum, or a superelastic alloy, such as nitinol. Preferably, thewire strands50A have a tensile strength in the range of 1800 to 2700 N/mm²but lower or higher values are also possible. Themetal core52 of thedelivery member15 may be made by winding themetal strands50A according to any method known to one skilled-in-the-art. For example, a group of about five to twelvewire strands50A having the desired wire diameter may be placed in a row next to or closely adjacent to each other. Thewire strands50A are then wound according to the desired pitch angle into an elongated,tubular metal core52. Because a row of wires is wound, eachindividual wire strand50A is restricted in movement by theother wire strands50A and is plastically deformed into a permanent helical shape which is kept without any further restraints other than each wire assists in keeping the other wires aligned in the row. The helical winding of thestrands50A forms alumen45 defined by theA-side47 of thestrands50A.

After being helically wound, the coiledwire strands50A can be subjected to heat treatment or drawing in order to further define the tubular structure and to reduce the presence of any residual stresses. For example, such a heat treatment may be performed over a period of about two to twenty hours at a temperature between about 400 to 600° C. Thewire strands50A in the resulting helically woundmetal core52 will maintain their position even when heavy torque is applied and themetal core52 is bent or pushed in a specific direction. Such resiliency results presumably because eachsingle wire strand50A is supported by the othercontiguous wire strands50A in thewound metal core52.

The size of the pitch angle (α) as defined inFIG. 6 depends on the width of thewire strands50A, the diameter of the desiredlumen45 and the number ofwire strands50A used to form themetal core52. The most preferred pitch angle for a catheter is in the range of 40° to 70° with the specific angle being determined by the desired balance in themetal core52 between torque transferability and transverse flexibility. The width (w₁) of theindividual wire strands50A is typically in the range of about 0.10 to 1.25 mm, and preferably in the range of 0.15 to 0.50 mm. The present invention includes providing a medical device having different segments wherein the row of wires is set to different pitch angles, or wherein different rows of wires have different pitch angles.

Referring now toFIGS. 5A-5H, each wire strand50(A, B) is a type of shaped wire with the shape being selected as one from the group of half round shaped D-wire60, less than half round shaped D-wire61, pie angle shapedwire62 with greater than about a 90° degree angle, triangular shapedwire63 having an obtuse angle, rectangular shapedwire64, square shapedwire65, flat shapedwire66, crescent shapedwire67, and combinations thereof. Preferably, the shaped wire is one selected from the group of half-round60 shaped wire, less than half-round61 shaped wire, triangular63 shaped wire, rectangular64 shaped wire, and combinations thereof.

Apolymer overlay55 is disposed about thewound wire strands50A that form themetal core52. Thepolymer overlay55 is provided on to the B-side48,53 of thewire strands50A,50B or the external surface of themetal core52. Thepolymer overlay55 may be a material coated onto the outer surface of the core52, a material extruded around thecore52, or a shrink tubing material that is pushed over thecore52. Thepolymer overlay55 is preferably a thin layer of an elastic material that extends along the entire length of thedelivery member15. Preferably thepolymer overlay55 will reduce the tendency of thedelivery member15 to stick to the vascular wall. Thepolymer overlay55 is typically applied after the winding and heat treatment of themetal core52 has been completed. For example, thepolymer overlay55 may be a PTFE coating applied onto the external surface of themetal core52 in the same manner as such a coating is traditionally applied onto the exterior of a guide wire. Thepolymer overlay55 as disposed about themetal core52, i.e., on the B-side48 of themetal strands50A, results in less than about a 5 to 15% increase in the outer diameter of thedelivery member15.

The composition of thepolymer overlay55 may include, but not be limited to, fluoropolymers, hyrdrophilic elastomers, polyolefins, and combinations or mixtures thereof. Several examples of fluoropolymers include ethylene-tetrafluoroethylene (ETFE), perfluroralkoxyethylene-tetrafluoroethylene (PFA), fluorinated ethylene propylene (FEP), copolymers of tetrafluoroethylene (TFE) and polytetrafluoroethylene (PTFE). Several examples of a hydrophilic coatings include crosslinked polyacrylates, copolymers of acrylic acid, polymethacrylate, polyacrylamides, poly(vinyl alcohol), poly(ethylene oxide), poly(ethylene imine), carboxymethylcellulose, methylcellulose, poly(acrylamide sulphonic acid), polyacrylonitrile, and poly(vinyl pyrrolidone). Several examples of polyolefins include polyethylene and polypropylene. One skilled-in-the-art will recognize that other biomedical polymers exist that are suitable for use as apolymer overlay55.

The hardness of thepolymer overlay55 disposed about themetal core52 can affect the flexibility associated with thedelivery member15. Hardness is one of the more important physiomechanical characteristics of a material that influences the ability of the material to resist elastic and plastic deformation of the material's surface. The term adequately applies to the resistance of a material against deformation that arises from indentation, scratching, cutting, or bending phenomena. In general, the application of a load that induces a shear strain in a material can cause the various structural elements of the material to become displaced relative to one another. The degree or magnitude of this displacement depends upon the hardness exhibited by the material and the magnitude of the applied load. In other words, the hardness exhibited by a material is a composite of multiple contributing factors, such as yield strength, work hardening, tensile stress, and modulus, rather than a basic property of the material itself. Hardness can be readily measured using a variety of standard test methods known to one skilled-in-the-art, including but not limited to Shore, Brinell, Vickers, and Rockwell testing. The hardness of thepolymer overlay55 can be predetermined and varied by modifying the contributing factors described above or through the incorporation of various types and amounts of inert filler materials, such as glass, silicon dioxide, and aluminum oxide, into thepolymer overlay55.

Thedelivery member15 can be made with a uniform diameter (d) throughout its elongated traverse length. When desired to enhance the flexibility of thedistal portion25 of thedelivery member15, thedistal portion25 as a whole or in specific locations may exhibit a diminishing wall thickness (T) associated with thewire strands50A in themetal core52. Such adistal portion25 may be fabricated by machining or grinding a region of thewire strands50A to a desired thickness dimension after they are helically wound into themetal core52.

This machined region can extend along the entire length of thedelivery member15, so that thedelivery member15 may exhibit a very precise outer dimension overall. In another aspect of the present invention, the machined region is part of thedistal portion25 of thedelivery member15. In this case, the machined region may be tapered, i.e., diameter decreases, which allows the device to exhibit increasing flexibility as one moves towards thedistal end30 of thedelivery member15. This increased level of flexibility in thedistal portion25 of thedelivery member15 facilitates the introduction of thedelivery member15 into very diminutive vessels. The reduced cross-sectional area of thewire strands50A produced by the machining operation greatly increases the bending flexibility of themedical device10 without sacrificing its ability to transfer torque.

As an alternative or supplement to grinding, thedelivery member15 may be composed of several segments in which the wires have mutually different thicknesses (T). However, the cross-sectional area of the lumen is maintained substantially similar between the different segments in order to prevent the occurrence of any obstruction to the advancement of a guide wire or other device through the lumen. The different segments may be joined together in axial extension by laser welding, soldering, bracing, or any other method known to one skilled-in-the-art.

Thedistal portion25 of thedelivery member15 may also be tapered towards itsdistal end30 in order to enhance an interaction with a guide wire. The taper can either be restricted to thedistal end30 or extend along any desired length of thedistal portion25 of thedelivery member15. Due to this taper, thedistal portion25 will benefit from gradually increasing transverse flexibility and a higher degree of softness.

In order to make thedistal end30 of thedelivery member15 more visible to enhanced fluoroscopy, thedistal end30 may optionally include some type of radiopaque material, such as gold, platinum, iridium, palladium, or rhodium, or a mixture thereof. If desired, the radiopaque material can be of annular shape located at a predetermined distance from the distal end or thedistal end30 of thedelivery member15 can be provided with a marker means for making it radiopaque, such as a gold layer or a gold thread.

The leak-free connector40 may be selected as any vacuum fitting or fluid fitting known to one skilled-in-the-art. Preferably the leak-free connector40 is a Luer-taper fitting, such as a Luer-Lok or Luer-Slip fitting. A Luer-Lok fitting utilizes a tabbed hub on the female portion of the fitting to engage threads positioned on the sleeve of the mating male portion of the fitting in order to achieve leak-free behavior. A Luer-Slip fitting typically utilizes frictional forces to maintain connectivity throughout the tapered fitting.

By making themetal core52 from a group of at least fivewire strands50A that are helically wound with a pitch angle roughly corresponding to the aggregate width of theadjacent strands50A, thestrands50A transfer torque and also force components directed in the axial direction of thedelivery member15, i.e., from theproximal end35 to itsdistal end30. Thus thedelivery member15 exhibits a very high resistance to kinking and less concentration of transmitted forces in areas where the delivery member bends due to the influence of the vascular walls.

Due to the flexibility, pushability, and ability to transmit torque, as well as the ability of thedelivery member15 to maintain each of these three characteristics themedical device10 can be used with very small and distant vessels, such as deep brain sites accessed by intracranial catheterization. In addition, thedelivery member15 of the present invention exhibits a more pronounced ability to transfer torque, low windup, whip, pushability, and use tension as other commonly used unifilar or multifilar coiled cannulas without sacrificing compression strength, hoop strength, or thin wall thickness.

In one embodiment of the present invention, the group or row of wires is made up of from about 5 to 12 helically wound wires, preferably from 6 to 9 helically wound wires. Since several wires are used, their aggregate width can be adapted to correspond to the desired pitch for the given diameter of the device. A row of more than 12 wires would have a tendency to buckle when the wires are helically wound in a conventional winding operation.

In order to promote uniform and well-defined characteristics along the entire length of themedical device10, thewire strands50A when positioned in a row are preferably located closely next to each other so that they can mutually contact and support each other. Any possible deflection of asingle wire strand50A is therefore reduced to a minimum by theothers strands50A located in the row. As the wires in the row are helically wound in a common movement a slight interstice can exist between the turns of the row of wires. The inside surface of themetal core52 of the present invention is found to be consistent, thereby, promoting the axial advancement of a guide wire or other device through thedelivery member15. The capabilities of torque and push are presumably a result of the mutual interlocking of theindividual wire strands50A wound into themetal core52. If onestrand50A has a tendency to kink or bend when a load is applied to thedelivery member15, theother wire strands50A will keep this strand in place due to the existence of a common helical path that interlocks this strand with theother strands50A.

In one embodiment of the present invention, thewire strands50A have a pitch angle in the range of about 25° to 77°, preferably a pitch angle in the range of 40° to 65°. Although it is possible to use other pitch angles, angles chosen in these ranges provide a balanced solution to the requirements for desired high flexibility, high column strength, and fine torqueability. The preferred range of 40° to 65° is useful for advancing a catheter through small sized vessels, such as in blood vessels in the brain. On the other hand, a pitch angle in the range of about 35° to 40° is useful when a very high degree of flexibility is required. A pitch angle in the range of about 70° to 75° is useful when the application calls for a very high amount of pushability. One skilled-in-the-art will realize that it is possible to choose different pitch angles in different segments of thedelivery member15.

Thewire strands50A are to a large extent mutually locked in position because thestrands50A are wound and drawn together. Thus onewire strand50A is kept in place by theother strands50A. However, some mutual movement can occur between thewire strands50A. Thepolymer overlay55 is useful in sealing any interstice that may exist between thewire strands50A, thereby, rendering thedelivery member15 leak-proof. The elasticity of thepolymer overlay55 allows small mutual movements of thewire strands50A to occur, thereby, imparting excellent flexibility to the helically woundmetal core52.

It is preferable that thedistal portion25 of thedelivery member15 be at least 30 cm in length with the maximum outer diameter of said distal portion being less than 2.0 mm. The maximum outer diameter of thedelivery member15 has a profound effect on suitable application of themedical device10. An outer diameter of less than about 1.00 mm allows the introduction of thedelivery member15 into fine, diminutive vessels, such as the external and internal carotid arteries. An outer diameter less than about 0.75 mm allows an operator to advance the delivery member into the liver and other soft tissue areas. An outer diameter less than about 0.30 mm in at least the last 10 cm length of thedistal portion25 before thedistal end30 makes distant vascular regions accessible allowing thedelivery member15 to be used as a neuro-microcatheter.

Individual features of the various embodiments can be combined into further embodiments according to the present invention. It is possible to deposit thepolymer overlay55 as a multilayer coating, e.g., a coating comprising a primer-coating and a top-coat where the primer-coating is chosen to provide strong bonding to thewire strands50A, and the top-coat providing the sealing and acting as a hydrophilic, low friction surface.

Another objective of the present invention is to provide a method for performing fibrinolysis by chemical infusion and/or the vacuum removal of emboli present in a vasculature of a patient. InFIG. 7, a method of addressing fibrin clots formed in a small vessel, such as an intracranial vasculature, is shown according to the teachings of the present invention. This method comprises the steps of introducing a sheath having a lumen into a blood vessel; inserting a guide wire through the lumen of the sheath; deploying the elongated tubular delivery member of a medical device having distal and proximal portions with a common lumen over the guide wire into the blood vessel; positioning the distal end of the delivery member proximate to a clot; removing the guide wire; injecting a fibrinolytic agent into the blood vessel through the delivery member until the clot is dissolved; and removing the delivery member of the medical device from the blood vessel.

Thedelivery member15 of themedical device10 has ametal core52 comprising multiple shaped-wire strands50A having an A-side47 and a B-side48, thewire strands50A helically wound to form alumen45 with its inner diameter being defined by theA-side47 of the strands and apolymer overlay55 disposed about the B-side48 of themetal core52; said helically woundwire strands50A further forming afirst polygon70 defined by the B-side48 of the strands and asecond polygon75 defined by theA-side47 of thestrands50A; thesecond polygon75 defining the shape of thelumen45. Themedical device10 further comprising aconnector40 engaged with the proximal portion of thedelivery member15. Theconnector40 being compatible for use with fibrinolytic agents, application of a vacuum, or both.

The step of positioning the delivery member proximate to the clot can be accomplished due to the rigidity of the proximal portion being greater than the rigidity of the distal portion. The step of injecting a fibrinolytic agent into the blood vessel through the delivery member until the clot is dissolved is facilitated by the metal core having an inside diameter that is less than about 1.25 mm and an outside diameter that is greater than about 0.30 mm; with the ratio of the inside diameter to the outside diameter being greater than about 1.5.

Themethod100 may further comprise the steps of applying a vacuum to through the delivery member to a clot that is only partially dissolved and removing the partially dissolved clot via the vacuum.

The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims (20)

1. A medical device for clot removal from small vessels by fibrinolytic infusion or vacuum retrieval, the device comprising:

an elongated tubular delivery member having a proximal portion and a distal portion, the delivery member comprising a metal core of multiple shaped-wire strands having an A-side and a B-side, the wire strands helically wound to form a lumen with an inner diameter defined by the A-side of the strands and a polymer overlay disposed about the metal core; the proximal portion and distal portion being different in their predetermined degree of rigidity; and

a leak-free connector in contact with the proximal portion of the delivery member; the connector being compatible for use with fibrinolytic infusion and vacuum retrieval;

wherein the helically wound wire strands form a first polygon defined by the B-side of the strands and a second polygon defined by the A-side of the strands; the second polygon defining the shape of the lumen.

2. The device ofclaim 1, wherein the first polygon inscribes a first circle having a radius, R₁, and the second polygon circumscribes a second circle having radius, R₂;

wherein the difference in magnitude between R₁and R₂is about equal to the thickness of the wire strands.

3. The device ofclaim 2, wherein the ratio of the area (A1) of the first polygon to the area (A2) of the second polygon is about equal to the quotient of:

[(R₁)²·cos²(π/N)]/(R₂)²,

where N is the number of wire strands.

4. The device ofclaim 1, wherein the difference in rigidity of the proximal and distal portions of the delivery member results from a variation in one of the wall thickness of the metal core, the hardness of the overlay, and a combination thereof.

5. The device ofclaim 1, wherein the shape of the wire strands that form the metal core is selected as one from the group of half round shaped D-wire, less than half round shaped D-wire, pie angle shaped wire with greater than about a 100° degree angle, triangular shaped wire having an obtuse angle, rectangular shaped wire, square shaped wire, flat shaped wire, crescent shaped wire, and combinations thereof.

6. The device ofclaim 1, wherein the hollow metal core has an inside diameter that is less than about 1.25 mm and an outside diameter that is greater than about 0.30 mm.

7. The device ofclaim 6, wherein the ratio of the inside diameter to the outside diameter is greater than about 1.5.

8. The device ofclaim 1, wherein the metal core is made up of at least 5 shaped-wire strands.

9. The device ofclaim 1, wherein the hollow metal core comprises two layers of helically wound shaped-wire strands; the second layer being disposed about the first layer.

10. The device ofclaim 1, wherein the polymer overlay is one selected from the group of a coated material, an extruded material, and a shrink tubing material; with the composition of the material being one selected from the group of fluoropolymers, hyrdrophilic elastomers, polyolefins, and combinations or mixtures thereof.

11. The device ofclaim 1, wherein the leak-free connector is one selected from the group of a Luer-lock fitting and Luer-Slip fitting.

12. The device ofclaim 4, wherein the variation in wall thickness of the core results from a grinding operation being performed on the outer diameter of the core's distal portion.

13. The device ofclaim 4, wherein the variation in wall thickness of the hollow core results from using at least one different core for the proximal portion and the distal portion that have substantially similar inner diameters, but different outer diameters;

wherein the distal end of the core used in the proximal portion of the delivery member and the proximal end of the core used in the distal portion of the delivery member are in contact with one another such that their inner diameters engage one another.

14. The device ofclaim 1, wherein the rigidity of the proximal portion is greater than the rigidity of the distal portion.

15. The device ofclaim 1, wherein the distal portion further comprises a distal end in which the inner diameter of the delivery member is tapered to contact and retrievably receive a guide wire.

16. The device ofclaim 1, wherein the multiple shaped-wire strands are helically wound with a pitch angle (α) between about 25 to 77 degrees.

17. The device ofclaim 1, wherein the distal portion of the delivery member further comprises a radiopaque material to enhance visibility during fluoroscopy; the radiopaque material being one selected from the group of gold, platinum, iridium, palladium, rhodium, and a mixture thereof.

18. The device ofclaim 1, wherein the wire strands are each angled in the same direction relative to a longitudinal axis defined by the lumen.

19. The device ofclaim 18, wherein the wire strands are parallel to each other.

20. A medical device for clot removal from small vessels by fibrinolytic infusion or vacuum retrieval, the device comprising:

an elongated tubular delivery member having a proximal portion and a distal portion, the delivery member comprising a metal core of multiple non-braided shaped-wire strands having an A-side and a B-side, the wire strands helically wound to form a lumen with an inner diameter defined by the A-side of the strands and a polymer overlay disposed about the metal core; the proximal portion and distal portion being different in their predetermined degree of rigidity; and

a leak-free connector in contact with the proximal portion of the delivery member; the connector being compatible for use with fibrinolytic infusion and vacuum retrieval;

wherein the helically wound wire strands form a first polygon defined by the B-side of the strands and a second polygon defined by the A-side of the strands; the second polygon defining the shape of the lumen.

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